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large deformation with the volume constant

Posted Jul 28, 2011, 9:32 p.m. EDT Structural Mechanics Version 4.1 2 Replies

Lingyao Yu
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Hello,

I 'm trying to simulate the deformed cell with solid mechanics module. The volume of the cell should be kept constant during the cell deformation. However, the volume is always changed after calculated.

I have tried some methods, for example, I use nearly incompressible material and geometric nonlinearity in the linear elastic material model. Many warnings come to say 'inverted mesh' and I can not get the final results. I can not find a good way to keep the volume of the cell constant. So, could you give me some suggestions?






Regards
Lingyao
2 Replies Last Post Aug 3, 2011, 9:32 a.m. EDT
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Jul 31, 2011, 12:21 a.m. EDT
You should switch to a hyperelastic formulation in order to get a constant volume. The key is in the way different formulations calculate volumetric strain. The linear elastic material with geometric nonlinearity uses the Green-Lagrange strain. A zero volumetric (mean) Green-Lagrange strain does not mean zero volume change. Hyperelastic materials use the determinant of the deformation gradient as a measure of volumetric strain so zero strain means zero volume change.

Nagi Elabbasi
Veryst Engineering
You should switch to a hyperelastic formulation in order to get a constant volume. The key is in the way different formulations calculate volumetric strain. The linear elastic material with geometric nonlinearity uses the Green-Lagrange strain. A zero volumetric (mean) Green-Lagrange strain does not mean zero volume change. Hyperelastic materials use the determinant of the deformation gradient as a measure of volumetric strain so zero strain means zero volume change. Nagi Elabbasi Veryst Engineering
Lingyao Yu
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Posted: 1 decade ago Aug 3, 2011, 9:32 a.m. EDT

You should switch to a hyperelastic formulation in order to get a constant volume. The key is in the way different formulations calculate volumetric strain. The linear elastic material with geometric nonlinearity uses the Green-Lagrange strain. A zero volumetric (mean) Green-Lagrange strain does not mean zero volume change. Hyperelastic materials use the determinant of the deformation gradient as a measure of volumetric strain so zero strain means zero volume change.

Nagi Elabbasi
Veryst Engineering


Thanks very much!

Best regards
Lingyao
[QUOTE] You should switch to a hyperelastic formulation in order to get a constant volume. The key is in the way different formulations calculate volumetric strain. The linear elastic material with geometric nonlinearity uses the Green-Lagrange strain. A zero volumetric (mean) Green-Lagrange strain does not mean zero volume change. Hyperelastic materials use the determinant of the deformation gradient as a measure of volumetric strain so zero strain means zero volume change. Nagi Elabbasi Veryst Engineering [/QUOTE] Thanks very much! Best regards Lingyao

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